Sinar focusing magnifier, Rodenstock / Schneider loups - need some feedback

[Mr. Rib]

Hi all.
I need a magnifying solution for a matte screen of my RZ, I decided to mod a focusing magnifier for view cameras. It may sound a bit crazy but for my next job I don't want to rely on live view for critical focussing, it would be too time consuming taking onto account the amount of products I need to shoot. I know a great guy who can build a custom magnifier for me, but I thought it would be wiser to simply modify a magnifier instead of building it from scratch.
Can anyone share with me his experience of Sinar focusing magnifier and rodenstock / Schneider loups? It needs to cover at least P45 back area in vertical / horizontal positions, so let's assume it's 49mm x 49mm.
If I'm totally crazy and this idea is plain stupidity, let me know as well

The Sinar magnifier I mentioned has a catalogue number 552.32.086. Here's a link to the image of it:
http://www.sinar.ch/images/stories/produktuebersicht/p3/p3_zub_50.jpg

[Audii-Dudii]

I have no experience with the Sinar magnifier, but I've done something similar to what you propose (I think, anyway) for my Contax 645 using this Mamiya Loupe:

http://cgi.ebay.com/Mamiya-3-5X-Loupe-/330404586174?pt=LH_DefaultDomain_0&hash=item4ceda5e2be

My original intention was to extract the optical elements and fabricate a "chimney" finder for them, but in the end, it turned out to work well enough just holding the loupe in place over the focus screen, so I have not bothered yet.  And since this loupe covers 6x6, there's plenty of coverage for your P45's sensor and, miracle of miracles, it's also nearly distortion free, so straight lines remain straight lines, even at the edges of the frame!

Mamiya also offered a 6x7 version of this loupe as well (both, alas, are NLA, so you'll have to buy used or find a NOS one for sale somewhere) but it's only 3X, so if you don't need the extra coverage, I'd go with the slightly greater magnification of the 645/6x6 version.

[EricWHiss]

I don't think your idea is crazy...I've tinkered with several different optics adapted to fit my rollei 6008 for magnified viewing and I don't see why this wouldn't work.  The Rodenstock 3x viewfinder is quite good and sold by Calumet under their own brand.  I think the Schneider is just a touch better but its more expensive.  Hasselblad made 4.5 x magnifier for use on the V series cameras that might work well and you can find on ebay lots of great stuff that might work for you.  The fuji 860 had a nice chimney finder that can be adapted and you can find lots of stuff on ebay that will work.  Theres a russian 4x finder that you can find on ebay that's actually quite good.  Never tried the Sinar one you've linked to but surely it would work as well.  

[BJNY]

Perhaps consider the LCD loupes for DSLRs:

http://www.zacuto.com/z-finder-dslr-viewfinder

http://www.bhphotovideo.com/c/product/677008-REG/LCD_Viewfinder_LCDVF.html

[Dick Roadnight]

Hasselblad made 4.5 x magnifier for use on the V series cameras that might work well

I think the original Hasselblad magnifying viewfinder for digital was for a very small format... perhaps they made several, but I doubt that anything they made for digital on the V system would cover 49mm * 49mm. There may be something for 6 * 6.

[tho_mas]

Can anyone share with me his experience of Sinar focusing magnifier and rodenstock / Schneider loups? It needs to cover at least P45 back area in vertical / horizontal positions, so let's assume it's 49mm x 49mm.

The Sinar loupe linked above is actually a Rodenstock loupe (3x maginfication), modified to fit in the finder-bellows of the Sinar cameras resp. groundglas frames.

Here's a link to the Rodenstock loupes: http://www.rodenstock-photo.com/en/main/products/magnifiers/aspherical-magnifiers/
specs: http://www.rodenstock-photo.com/mediabase/original/e_Rodenstock_Magnifiers_74-75__8229.pdf

I use the 6x loupe for focusing a tech camera on the groundglas; it is very clear and contrasty.

[Mr. Rib]

Thank you for all your anwsers, it encourages me to do it and I'm not crazy after all
The only downside of the Sinar's (in fact Rodenstock's) loupe is that it's maginification factor is 3x. Since the view camera loupes are ok for this, I tink I'd rather go for stronger magnification. Rodenstock 6x loupe covers a circle with diameter of 57mm, which gives a 40mm x 40mm square. That's just a bit too small for my application, would it be ok if I attached a bellows underneath the loupe making it possible to slightly move the loupe across RZ67 matte screen in all directions (let's assume that the other part of the bellows is connected to the camera in the same manner a standard RZ67 chimney would connect)? I have no experience with view camera loupes so I'll rely on your anwsers with this matter.

[EricWHiss]

I think the original Hasselblad magnifying viewfinder for digital was for a very small format... perhaps they made several, but I doubt that anything they made for digital on the V system would cover 49mm * 49mm. There may be something for 6 * 6.

Yes it will cover the 36x48 sensors.  I fit one to my rollei. I can see the whole focusing screen but am not able to read the internal display which isn't too much a problem for me.  I appreciate the extra magnification.    I will say that the schneider 3x loupe is a bit brighter so there are trade offs.   For some lenses like the 110mm f/2 it doesn't matter and the extra magnification is appreciated, however for other lenses with smaller max apertures the schneider works better for me.

[lookit]

There is a Mamiya magnifier that clips onto the prism eye hole in place of the eyecup. I don't think the entire focusing screen is visible through it but the mount is hinged so it can temporarily swing out of the way.